In an electric power steering device, the output of an electric motor is reduced in speed through a worm and a worm wheel, and then transmitted to a steering mechanism, thereby assisting the torque of the steering operation.
Backlash is required in meshing between a worm and a worm wheel. During traveling, however, there is a possibility that a rattle sound due to backlash may be generated.
Conventionally, therefore, an electric power steering device has been proposed in which a bearing for supporting a worm is elastically urged toward a worm wheel to eliminate backlash.
A technique has been proposed in which, is such an electric power steering device of the type in which a bearing for supporting a worm is elastically urged toward a worm wheel to eliminate backlash, the bearing for supporting the worm is axially preloaded to eliminate play of the bearing, whereby an abnormal sound due to play of the bearing is prevented from being generated (for example, see Patent Literature 1).